https://twitter.com/kot_2010/status/454482017439453184

gistfile1.cs

class MyOld5700LoCBusinessClass { // actually 5715 lines

	bool flag1, flag2, ..., flag15;
	string message1, message2, ... message15;
	// more instance variables

	void Method1() {...}
	...
	void Method30() {...}

	void Method31() {
		// 1000 lines of code mutating many instance variables and reading others. Grossly simplified here to illustrate the concept.
		flag4 = true;
		flag6 = false;
		message4 = "hello";
		if (flag5) message5 = "byebye";
	}

	// more methods
}

Refactor Method31 to:

static void Method31(bool flag5, out bool flag4, out bool flag6, out string message4, ref string message5) {
	flag4 = true;
	flag6 = false;
	message4 = "hello";
	if (flag5) message5 = "byebye";
}

void Method31() {
	Method31(flag5: flag5, flag4: out flag4, flag6: out flag6, message4: out message4, message5: ref message5);
}

Now I can tell more precisely which instance variables Method31 uses and how (read/write)

Huh. I see. It seems you have to deal with a really awful codebase :(